ADHD and the Forgotten Gender: Why Is ADHD Underdiagnosed In Girls?

Noisy, fidgety, impatient, hyper: this is what the average person imagines when they think of a child with ADHD. They normally also imagine that the child is a boy. Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder, characterised by a persistent set of symptoms which include hyperactivity, inattention, distractibility, and impulsiveness, in many different combinations and to varying degrees. It is one of the most prevalent childhood disorders, affecting up to 5% of children worldwide.

There are three types of ADHD, as outlined in the Diagnostic and Statistical Manual of Mental Disorders (DSM): ADHD Primarily Inattentive Type, ADHD Primarily Hyperactive-Impulsive Type, and Combined Type ADHD. The symptoms of each condition can be classified as mild, moderate, or severe. The disorder persists into adulthood in up to 30% to 70% of patients.

ADHD over-diagnosis is a well-known topic and oft-talked of debate. The percentage of school-age children receiving a diagnosis has been on the rise for decades. It is argued that over-diagnosis incites over-treatment and ADHD medication, such as psychostimulant drugs Ritalin (methylphenidate) and Adderall (amphetamine-dextroamphetamine), in the wrong hands can prove fatal, owing to their high abuse potential. However, many have attributed rising ADHD diagnoses to increased awareness about the disorder, as well as the broadening of the diagnostic criteria; shining light on the fact that the increasing diagnosis rates may actually be due to a correction in the previous under-diagnosis of certain patient groups.

Overdiagnosis has received constant attention in the media but there is another, arguably more detrimental, issue surrounding ADHD diagnosis rates which has not received nearly as much attention: under-diagnosis of ADHD in women. The male-to-female ratio of those diagnosed with ADHD is approximately 4:1, with ratios reaching as high as 9:1 in certain community samples. Despite huge skews in diagnosis rates, ADHD is thought to be an ‘equal-opportunity condition’ with regards to gender. In clinical studies, the gender imbalance is almost non-existent. Analysis has estimated that half to three‐quarters of all women with ADHD go undiagnosed or are misdiagnosed with other disorders such as anxiety or depression.

The lower rates of ADHD diagnosis in girls could be attributed to a combination of factors. The diagnostic standards still chiefly in place today were formulated based on data collected from studies completed in the 1970s that were conducted on largely all-male cohorts. This fact has a number of repercussions: first, the original diagnostic criteria designed by the American Psychiatric Association required ADHD-like symptoms to be present by the age of 7 (although this age has been increased to 12 years old in the latest DSM edition) for a child to be diagnosed with the disorder. ADHD symptoms typically do not emerge in females until the onset of puberty, with girls, on average, being diagnosed 5 years later than their male counterparts. As a result, miseducated teachers or parents often assume that the ‘diagnostic window’ has closed for a girl displaying archetypal ADHD symptoms, and disregard the symptoms.

A second explanation for underdiagnoses could be the different symptom profile of ADHD in women in comparison with ADHD in men. Men are more likely to present with the ‘hyperactive-impulsive’ or combined type form of ADHD, whereas women are typically more prone to the less overt and less disruptive ‘inattentive’ forms of ADHD, or what is colloquially referred to as ADD (attention-deficit disorder). Girls are more likely to be labelled as ‘daydreamers’ in the classroom, rather than having their symptoms be seen as something that is out of their control. Additionally, girls may attempt to mask or compensate for their symptoms, trying harder in academia or making a marked effort to be more attentive in social situations with their peers. This pattern of compensatory behaviour may be an additional factor contributing to decades of overlooking symptoms in women and girls.

Consultant child and adolescent psychiatrist and UCD professor Dr. Fiona McNicholas deems implicated professional parties, such as GPs and teachers, to have the greatest amount of responsibility to educate themselves thoroughly on the disorder, in order to ensure incidences of missed or delayed diagnoses are reduced. ‘They need to be looking out for the quiet, inattentive kid just as much as the hyperactive or impulsive kid.’ Dr. McNicholas believes that the ‘under-recognition in adolescence finally redeems itself when the adult patient is able to recognise their own problems and can self-refer’. The gender scales become balanced in adulthood, as women are ‘more proficient at emotional health-seeking than males’, while men are less likely to seek help at a professional level. Prevalence rates of ADHD amongst adults are much more similar between men and women, closer to 1:1 ratio which is expected.

Passing under the ADHD diagnostic radar as a child has been shown to have severe repercussions in later life, for both academic and psychosocial development. It has been linked to an increased predisposition for the development of anxiety, depression, personality disorders, and substance abuse in adulthood. Longitudinal studies ‘show negative consequences in terms of mental health status, failed academic attainments, poor job prospects, troubled relationships and increased chance of entering the criminal justice system,’ said Dr. McNicholas. Considering these facts, it is clear that an early diagnosis is imperative to the wellbeing of women with ADHD. Thankfully Dr. McNicholas believes the tides are turning. She believes gender bias at a clinical level is ‘less of an issue these days, as the literature supporting equal levels of incidence rates has increased’ with each passing year, and that awareness regarding the issue is on the rise, with the gap finally beginning to close. Nonetheless, raising awareness amongst the public will be absolutely necessary if we are to close the diagnosis gap, as teachers and parents are incapable of referring girls in need if they aren’t capable of spotting the signs.